Patent GB-1073741-A (GB)
Title: Process and apparatus for producing multifilament material and products produced therefrom
Inventor: SLACK PHILIP TREVOR
IPC: B29C48/08
Filed: 1962-08-30
Abstract: A process for the production of multi-filament material comprises splitting, cutting or slitting a continuously moving strip, tube or sheet of synthetic resinous material orientated in a longitudinal direction into a plurality of strands, adjacent strands being integrally joined together at regularly spaced intervals along the length thereof by bringing a plurality of cutting edges or needles disposed in spaced, parallel and staggered relationship over the surface of a rotating drum consecutively into a cutting relationship with said moving strip, tube or sheet.  Suitably said strip or sheet of orientated material has a thickness of 380 microns or less, especially not more than 250 microns.  Alternatively, said strip or sheet of oriented material may have a thickness of not greater than 15 thousandths of an inch, and especially a thickness of 10 thousandths of an inch.  Specified synthetic materials include polyalkenes, polyamides and polyesters, e.g. polyethylene, polypropylene, nylon, and polyterephthalic esters.  Desirably, the said sheet, tube or strip is under tension when it is split, cut or slit.  Fibres may be made from such multifilament material and rope, twine, cord, yarn or textile material may be made from such fibres. Multi-filament material produced by the method of the invention or a fibre or yarn produced therefrom may be passed between two relatively moving surfaces for a period of time and under sufficient pressure to produce a bulking effect on the material, fibres or yarn.  A scribbling or lapping device is suitably used in such a process.  In apparatus as shown (Figure 1A, not reproduced) synthetic resinous material fed into an extruder 10 are heated and extruded through die 12, through which air is simultaneously blown, thus forming a tube 14, which is passed through air cooling ring 16 and nip rollers 18 and the tube 14, in the flattened state, is then passed over a series of tension rolls 1, 2, and 3.  A slitter 20 is provided between tension rolls 2 and 3, which slits the edges of tube 14 thus providing two sheets 22 and 24.  Each of the sheets either direct from the slitter or from storage rolls is then passed through a series of rolls 26, a hot water bath 28 (or hot air chamber), and then through a second series of rolls 30, which rotate at a speed faster, preferably five to ten times faster, than the speed of rolls 26.  This speed differential together with the heating effect provided by the water bath, which is preferably at 80 to 100 DEG C., especially 98 to 100 DEG C., results in the orientation of the sheet material.  The orientated sheet material is then split, cut or slit by a rotating slitter 32 which is driven and the multi-filament material so produced collected on a series of collecting rolls 34. If a tube is required, slitter 20 will be absent, and if strip material is required, a further slitter having a plurality of cutters would be positioned before the first set of rolls 26, and a plurality of orientating equipment would be provided one for each strip produced.  The water bath may be replaced by a steam jacket, or by a heated contact plate.  100 DEG C. is a suitable orientation temperature for polyethylene, but for polypropylene orientation temperatures of about 120 DEG C. are more suitable, so that the contact plate method is then preferred. When using the contact plate the sets of rolls 26 and 30 may each be replaced by a set of nip rollers of which the driven roller is made of steel and the other roller is free running and has a rubber surface.  Advantageously, the splitting, cutting or slitting takes place while the sheet material is under tension and a further set of rolls similar to rolls 26 may therefore be inserted between slitters 32 and collecting rolls 34. These additional rolls are preferably run at a speed 3 to 5% greater than rolls 30 to produce the tensioning effect.  An example is given.